Kirki allows you to change the styling of the customizer using the kirki_config filter:

<?php/**
* Configuration sample for the Kirki Customizer.
* The function's argument is an array of existing config values
* The function returns the array with the addition of our own arguments
* and then that result is used in the kirki_config filter
*
* @param $config the configuration array
*
* @return array
*/functionkirki_demo_configuration_sample_styling($config){returnwp_parse_args(array('logo_image'=>'https://aristath.github.io/kirki/images/logo.png','description'=>esc_html__('The theme description.','kirki'),'color_accent'=>'#0091EA','color_back'=>'#FFFFFF',),$config);}add_filter('kirki_config','kirki_demo_configuration_sample_styling');

logo_image: Change the logo image (URL). If omitted, the default theme info will be displayed. You may want to use a relatively large image (for example 700px wide) so that it’s properly displayed on retina screens as well.

description: Changes the theme description. Will be visible when clicking on the theme logo.

color_accent: The accent color. This will be used on selected items and control details.

color_back: The background color. This will be used on sections & panels titles.

width: The width of the customizer. Use any valid CSS value like for example 24%, 400px, 25em etc. In case you decide to change the width, please take into account mobile users as well.

disable_loader: set to true if you want to disable the custom Kirki loader and use the WP Core default.

Licence

Kirki is licenced under the MIT Licence. It is 100% open-souce and you can use it on your projects.

Though not legally necessary, we would appreciate if you mention in your project's page that use Kirki and link to this project.

Support

Support is provided from the github repository. Though we do our best to reply to everyone in a timely manner and address any questions or issues you might have, keep in mind that Kirki is an open-source project maintained by people donating hundreds of hours.